1. Field of the Invention
This invention relates to a method for the in situ cleaning of a process chamber. Specifically, a chlorine-based cleaning is performed in a chemical vapor deposition ("CVD") chamber to improve deposition process conditions and wafer-to-wafer repeatability.
2. Description of the Background Art
Semiconductor processing typically is carried out in specialized apparatus comprised of multiple chambers wherein wafers are processed by the deposition and various treatments of multiple layers of semiconductor material in a single environment. In such tools, the plurality of processing chambers and preparatory chambers are arranged in clusters, each served by robotic transfer means. Hence, such tools are commonly referred to as cluster tools. Such tools process semiconductor wafers through a plurality of sequential steps to produce integrated circuits.
Regardless of whether semiconductor processing apparatus is configured as described above or in other arrangements known to those skilled in the art, it will be appreciated that the objective is simply to process the greatest number of wafers per unit of time in the most efficient manner. However, it is characteristic of all such apparatus that active chambers, i.e. those wherein semiconductor material is deposited or treated in some other manner, such as etching, must periodically be cleaned of the residues inherently formed during such procedures. It will further be appreciated that it is desirable to have as high a throughput as possible without sacrifice of the quality of the operation carried out in a deposition chamber before it must be cleaned.
One particularly desirable feature of cleaning a deposition chamber is to perform the cleaning in situ, i.e. without the necessity of removing the chamber from the cluster tool or exposing the chamber to oxidizing elements present in the atmosphere. In situ cleaning would mean that the cluster tool would not have to be turned off while one or more chambers are cleaned. This is particularly advantageous when it is considered that chambers where different semiconductor processes are carried out become unsuitable for efficient processing at different rates and, hence, do not require cleaning at the same time. Therefore, a process whereby one or more chambers in a multiple chamber tool can be cleaned while others continue to perform their function in the process is particularly advantageous. A cleaning process that meets the needs described above is provided in accordance with the present invention.